Mark-recapture may reveal more about ecology than about population trends: Demography of a threatened ghost bat (Macroderma gigas) population

Since European settlement in Australia, the geographical range of ghost bats (Macroderma gigas) has contracted northwards. Ghost bats are thought to occur in disjunct populations with little interpopulation migration, raising concerns over the current status and future viability of the southernmost colony, which has also been threatened by mining activity. To address these concerns, demographic parameters of the southernmost colony were estimated from a mark-recapture study conducted during 1975-1981. Female bats gave birth to a single young in late spring, but only 40% (22-70%, 95% CI) of females bred in their second year, increasing to 93% (87-97%, 95% CI) for females greater than or equal to 2 years old. Sixty-five percent of juveniles caught were female. Annual adult survival ranged between 0.57-0.77 for females and 0.43-0.66 for males, and was lowest over winter-spring and greatest in autumn-winter. Juvenile survival for the first year ranged between 0.35-0.46 for females and 0.29-0.42 for males. Adult survival varied among seasons, was negatively associated with rainfall, but was not associated with temperature beyond being lower in late winter. Poor survival may result from the inferior daytime roosts that bats must use if water seepage forces them to leave their normal roosts. Although these age-specific rates of fecundity and survival suggested a declining population, mark-recapture estimates of the population trend indicated stability over the study period. Counts at daytime roosts also suggested a population decline, but were considered unreliable because of an increasing tendency of bats to avoid detection. It is therefore likely that some assumptions in estimating survival were violated. These results provide a caution against the uncritical use of population projections derived from mark-recapture estimates of demographic parameters, and the use of untested indices as the basis for conservation decisions.

Application of spatial analysis techniques to adjust for fertility trends and identify interplot competition in early stage sugarcane selection trials

Most sugarcane breeding programs in Australia use large unreplicated trials to evaluate clones in the early stages of selection. Commercial varieties that are replicated provide a method of local control of soil fertility. Although such methods may be useful in detecting broad trends in the field, variation often occurs on a much smaller scale. Methods such as spatial analysis adjust a plot for variability by using information from immediate neighbours. These techniques are routinely used to analyse cereal data in Australia and have resulted in increased accuracy and precision in the estimates of variety effects. In this paper, spatial analyses in which the variability is decomposed into local, natural, and extraneous components are applied to early selection trials in sugarcane. Interplot competition in cane yield and trend in sugar content were substantial in many of the trials and there were often large differences in the selections between the spatial and current method used by the Bureau of Sugar Experiment Stations. A joint modelling approach for tonnes sugar per hectare in response to fertility trends and interplot competition is recommended.

Long-term trends in sunshine duration and its association with schizophrenia birth rates and age at first registration - data from Australia and the Netherlands

Back ground. Based on the well-described excess of schizophrenia births in winter and spring, we hypothesised that individuals with schizophrenia (a) would be more likely to be born during periods of decreased perinatal sunshine, and (b) those born during periods of less sunshine would have an earlier age of first registration. Methods. We undertook an ecological analysis of long-term trends in perinatal sunshine duration and schizophrenia birth rates based on two mental health registers (Queensland. Australia n = 6630; The Netherlands n = 24, 474). For each of the 480 months between 1931 and 1970, the agreement between slopes of the trends in psychosis and long-term sunshine duration series were assessed. Age at first registration was assessed by quartiles of long-term trends in perinatal sunshine duration, Males and females were assessed separately. Results. Both the Dutch and Australian data showed a statistically significant association between falling long-term trends in sunshine duration around the time of birth and rising schizophrenia birth rates for males only. In both the Dutch and Australian data there were significant associations between earlier age of first registration and reduced long-term trends in sunshine duration around the time of birth for both males and females, Conclusions. A measure of long-term trends in perinatal sunshine duration was associated with two epidemiological features of schizophrenia in two separate data sets. Exposures related to sunshine duration warrant further consideration in schizophrenia research. (C) 2002 Elsevier Science B.V. All rights reserved.

Hyperinsulinism and overgrowth without obesity

We report a 5 year old girl with postnatal overgrowth (height velocity >97th centile), hyperinsulinaemia, and increased insulin-like growth factor 1 for age, without evidence of bioactive or immunoreactive growth hormone excess or pituitary abnormality. Although her overgrowth may be a result of hyperinsulinism, her serum contains a factor (neither insulin nor IGF-1) which is able to stimulate the proliferation of lymphocyte precursors, and this could also account for the overgrowth. Over the course of two years observation she has developed acanthosis nigricans and diabetes mellitus.

Sitting time and work patterns as indicators of overweight and obesity in Australian adults

BACKGROUND: Increasing levels of physical inactivity and sedentariness are contributing to the current overweight and obesity epidemic. In this paper, the findings of two recent studies are used to explore the relationships between sitting time ( in transport, work and leisure), physical activity and body mass index (BMI) in two contrasting samples of adult Australians. METHODS: Data on sitting time, physical activity, BMI and a number of demographic characteristics were compared for participants in two studies-529 women who were participants in a preschool health promotion project ('mothers'), and 185 men and women who were involved in a workplace pedometer study ('workers'). Relationships between age, number of children, physical activity, sitting time, BMI, gender and work patterns were explored. Logistic regression was used to predict the likelihood of being overweight or obese, among participants with different physical activity, sitting time and work patterns. RESULTS: The total reported time spent sitting per day ( across all domains) was almost 6 h less among the mothers than the workers (P

Obesity is associated with worse peritoneal dialysis outcomes in the Australia and New Zealand patient populations

Although obesity is associated with increased risks of morbidity and death in the general population, a number of studies of patients undergoing hemodialysis have demonstrated that increasing body mass index (BMI) is correlated with decreased mortality risk. Whether this association holds true among patients treated with peritoneal dialysis (PD) has been less well studied. The aim of this investigation was to examine the association between BMI and outcomes among new PD patients in a large cohort, with long-term follow-up monitoring. Using data from the Australia and New Zealand Dialysis and Transplant Registry, an analysis of all new adult patients (n = 9679) who underwent an episode of PD treatment in Australia or New Zealand between April 1, 1991, and March 31, 2002, was performed. Patients were classified as obese (BMI of greater than or equal to30 kg/m(2)), overweight (BMI of 25.0 to 29.9 kg/m(2)), normal weight (BMI of 20 to 24.9 kg/m(2)), or underweight (BMI of